Gas burners



1965 H. H. BLIEVERNICHT 3,200,871

GAS BURNERS Filed Feb. 28, 1963 FIG. I

FIG. 2

IN VENTOR.

HARLAN H. euevsnmcmt r ham/ Z gToRNEY.

United States Patent Oflice 3,200,871 Patented Aug. 17, 1965 3,2dtl,371 GAS BURNERS Harlan H. Blievernicht, Lawrence, Ind, assignor to Carrier Corporation, Syracuse, N.Y., a corporation of Delaware Filed Feb. 28, 1963, Ser. No. 261,695 2 Claims. (Cl. l587) This invention relates to gas burners, and, more particularly, to an improved gas burner having means for automatically providing quiet and eificient operation thereof.

Gas burners of the type described herein burn a gaseous fuel, such as vaporized liquid petroleum, and may suitably comprise an elongated horizontal sheet metal burner body member disposed in an atmosphere of secondary air. The gaseous fuel is injected from a gas orifice into an open end of the burner body while at the same time inducing a quantity of primary air into the interior of the burner body due to the velocity of the gas stream. The induced primary air mixes with the gaseous fuel in the burner body and is ejected through one or more burner outlet ports into the atmosphere of secondary air where the mixture is ignited and burned.

One of the difficulties encountered in the operation of gas fired devices, such as gas heaters and furnaces, is the tendency of a gas burner to resonate or howl when it is initially ignited because excess primary air is supplied to the burner during initial operation thereof in order to provide the quantity of air which is required after the burner has heated up. This problem exists because the quantity of air which is induced into a gas burner of the type described automatically decreases as the burner heats up. However, it has been found that if excess air is initially supplied to the gas burner before it heats up so that sufficient air is supplied to the burner when it warms up, the burner exhibits the tendency to resonate or howl during initial operation. Generally, this effect, which is referred to as resonance, is only experienced during the first few minutes after initial firing of a gas burner, when it is relatively cold, but the noise is exceedingly annoying to the user.

It has been found that the tendency of gas burners to resonate or howl can be eliminated by reducing the quantity of primary air which is supplied to the burner during initial operation to an empirically determinable quantity below which the burner does not operate noisily. Unfor i'unately, however, if the quantity of primary air is limited to that quantity which does not produce noisy operation, as a gas burner heats up and reaches a steady state operating condition, the quantity of primary air induced into the burner becomes less than that which is required for efficient operation. Characteristically, after a short period of time, the gas burner burns with a yellow or red tipped flame which is indicative of inefiicient combustion, under which conditions the fuel produces less heat than it should, and, in addition, the burner undesirably tends to deposit soot on the interior surfaces of the gas furnace and flue pipes with which it is associated.

Accordingly, it is the principal object of this invention to provide a gas burner assembly which is capable of quiet and efficient gas burning during all periods of operation thereof.

It is a further object of this invention to provide a gas burner assembly with means to automatically control the quantity of primary air induced into the burner.

These and other objects of this invention are achieved in the illustrated preferred embodiment thereof by providing a hollow sheet metal burner body having an open end for a relatively high velocity stream of gaseous fuel which induces primary air into the interior of the burner body. A bimetallic strip projects into the interior of the burner body so as to inhibit the free flow of gas through th interior of the burner while at the same time not completely preventing its passage therethrough. By inhibiting the free flow of gas into the interior of the burner body, the quantity of primary air induced therein is also reduced during initial operation of the burner. The bimetallic strip is disposed in the burner body in such a manner that when the burner and bimetallic strip heat up, the strip reduces the obstruction of the free flow of gas through the burner body, thereby giving rise to the induction of a greater quantity of primary air therein. Consequently, the quantity of primary air induced into the interior of the burner body is automatically adjusted to overcome the tendency of the burner to resonate during initial operation, while at the same time, quiet and efficient burning of the fuel mixture is automatically achieved during steady state operation.

These and other objects of this invention will become more readily apparent by reference to the following detailed description and attached drawing, wherein:

FIGURE 1 is a cross-sectional view partially broken away through a gas furnace embodying the instant invention;

FIGURE 2 is a fragmentary longitudinal cross-sectional view through an improved burner assembly; and

FIGURE 3 is a cross-sectional view through the improved burner assembly taken substantially on line IIIIII of FIGURE 2.

Referring particularly to the drawing, there is shown in FIGURE 1 a gas furnace, generally designated 10, of a type adapted to employ a gaseous combustible fuel, such as vaporized liquid propane, as a heat source. Gas fur nace it) comprises an air-to-air heat exchanger 11, one side of which carries air to be heated, and the other side of which carries the hot exhaust gases from a burner assembly 12.

Air to be heated passes from a suitable duct or other inlet into plenum chamber 15 where it is blown by centrifugal fan 16 through the heated air side 17 of heat exchanger 11. The air which is heated in heat exchanger Ill then passes through a duct 18 by which it is distributed to a desired location.

A plurality of gas burner assemblies 12'; (only one of which is illustrated) are disposed within heat exchanger 11 on the side thereof which carries the hot flue gas from the burner which pass in heat exchange in relation with the air passing through heated air side 17 thereof. Burner assembly 12 comprises an elongated generally horizontal hollow sheet metal burner body 24 shown in greater detail in FIGURES 2 and 3. Burner body 24 is provided with at least one and preferably a plurality of burner ports 25, as shown, which discharges gas and primary air into an atmosphere of secondary air within the flue gas side of heat exchanger 11. It will be understood that secondary air is admitted to the flue gas side of heat exchanger 11 through opening 30 in the side of furnace til. Burner body 24 may also be provided with a carry-over port 26 for the purpose of spreading the gas flame to adjacent burners (not shown).

Burner body 24 may be formed by nestling a suitable shaped top member 40 in a channel shaped bottom member 41 and securing the two members together by spot welding at 43. The upwardly extending flanges of either or both of the channel shaped top and bottom members 40 and 41 may be provided with struck-out lip portions which cooperate to provide burner ports 25 when the members are joined to form the burner body, as shown in the drawing. Desirably, one end of burner body 24 is left open and provided with an axially slidable insert which forms an air shutter 29.

A gas main 22 is connected to a suitable source of gaseous fuel, such as a tank of liquefied petroleum, and

is provided with a gas orifice 23 adjacent the open end of each of the burner bodies 24 in gas furnace 10. Gas orifice 23 is positioned so as to inject a stream of the gaseous fuel into the interior of, burner body 24. Top member 49 of the burner body is provided with an axially extended portion having an aperture 23 therein for reception of a suitable locating pin 27 secured to gas main 22 for the purpose of positioning the burner body with respect to the gas main. Air shutter 2h may then be telescopically positioned in burner body 24 to make a fine adjustment so that, during normal operation, sufficient primary air is induced into the open end of the burner body by the. stream of gas ejected through gas orifice 23 to provide a satisfactory fuel mixture for efficient combustion.

In accordance with this invention, a bimetallic strip 35 is secured such as by rivets 38 to top member as of burner body 24. Bimetallic strip 35 may have a damper member 36 secured thereto by rivets 37, if desired, although the bimetallic strip may be made of such size and located so as to eliminate the necessity of a separate damper member. The bimetallic strip 35 may be suitably secured to any of the walls of burner body 24 or may be otherwise positioned with respect to the burner body and gas orifice 23 so as to project into and disturb the free flow and passage of gas from orifice 23 through the interior of the burner body when in a relatively cold condition. Strip 35 and damper 36 have an area less than the cross-sectional area of the passage through burner body 24 so that some air and gas can always pass to burner ports 25.

In operation, gaseous fuel is injected into the open end of burner body 24 through tubular air shutter 29. Tubular air shutter 29 is adjusted axially to provide sufficient clearance between gas main 22 and burner body 24 so that during normal operation the stream of gas injected into the burner body induces the desired quantity of primary air into its interior for mixing with the gas therein. Air shutter 29 may, of course, be omitted although its use is desirable to compensate for manufacturing and assembling tolerances.

As previously explained, the problem of resonance in a burner system arises because too much air is initially fed to the gas burner, and the problem can be solved by restricting the amount of air which is induced into the gas burner. However, because of the characteristics of the gas burner, the quantity of primary air which is induced into the burner body characteristically decreases as the burner body heats up from a relatively cool condition to a relatively warm condition. Consequently, if the gas burner assembly is designed and adjusted so that sufiicient primary air is induced into the burner body to promote efiicient combustion when the burner is in a relatively warm condition, it frequently occurs that the greater quantity of air which is induced into the gas burner when it is in a relatively cold condition is sufiicicut to give rise to resonance. Accordingly, a problem exists in operating the gas burner efficiently during normal operation when it has warmed up, while at the same time attempting to operate the burner quietly during the initial operation when the burner is relatively cold.

By the practice of this invention, the quantity of primary air induced into the gas burner assembly may be made nearly constant over any range of operating temperature thereby eliminating the problem described above. .When burner body 24 is in a relatively cold condition, bimetallic strip 35 and damper 36 secured thereto assume the position shown in FIGURES 2 and 3. In this condition, the bimetallic strip disturbs or restricts the free flow of gas through central passage 33 by projecting into the passage in the burner body. For this reason, less primary air is induced into central passage 33 from the open end of burner body 24 than would be the case if bimetallic strip 35 were not provided.

.As burner body 24 heats up to a relatively warm condition, bimetallic strip 35, which is in heat exchange relation therewith, is also heated. Heating of the bimetallic strip 35 causes it to flatten out withdrawing and decreasing the obstruction which it presents in central passage 33, thereby decreasing the inhibitions to the free flow of gas through the central passage. Since the gas .may then pass freely at high velocity through central passage 33, a larger quantity of primary air is induced into the open end of burner body 24 than when the obstruction is greater.

As the obstruction to the flow of gas through the burner is presented by the bimetallic strip varies, it will be apparent that the quantity of primary air induced in the burner is likewise varied.

By suitable selection of the geometry of burner body 24 with respect to gas main 22 and gas orifice 23, and by suitably shaping bimetallic strip 35 and damper 36, if used, the increase in the quantity of primary air induced into burner body 24 when it heats up may be made to compensate for the usual reduction in the quantity of primary air which is normally experienced when the burner body heats up. At the same time, the quantity of primary air initially induced into the burner body need not be greater than that quantity of air which gives rise to resonance or noisy operation when the burner is cold and initially ignited.

It will be seen that by the practice of this invention there is provided a simple and effective methodand means for operating a gas furnace in a quiet and efiicient manner, both when it is in a relatively cold condition and relatively warm condition. It will also be seen that the quantity of primary air induced into a gas burner in accordance with this invention may be automatically varied to provide a relatively uniform quantity of primary air irrespective of Whether the burner is in a relatively hot or a relatively cold condition. Furthermore, a gas burner assembly in accordance with this invention possesses unique advantages of simplicity and reliability, While being inexpensive to manufacture. It will also be noted that an existing gas burner body of the type described herein may be readily modified to include this invention, should it be found to produce noise during initial operation, by merely riveting or otherwise securing a bimetallic strip to one of the walls of the burner body, and without requiring further modification of the gas furnace or burner.

While for purposes of description a preferred embodiment of this invention has been illustnated and described, it will be appreciated that the invention may be otherwise embodied within the scope of the following claims.

I claim:

1. A burner assembly for burning a combustible gaseous fuel mixed with air which comprises: an elongated hollow sheet metal burner body adapted to be operatively positioned in a combustion chamber subject to a resonance condition when said burner is ignited, said burner body having an open end for receiving a stream of gas to be burned and for receiving a quantity of primary air induced into said burner body by the action of said stream of gas, said burner body having a burner port for discharging a mixture of gas and primary air from said burner body into an atmosphere of secondary air in said combustion chamber for burning of said gas, a bimetallic strip attached to said burner body and projecting into the hollow interior thereof in contact with the stream of mixed fuel and primary air therein, said bimetallic strip being arranged to obstruct flow of gas th ough said burner body when said bimetallic strip is in a relatively cold condition so as to limit the quantity of primary air induced into said burner body by said gas stream to an amount which does not give rise to said resonance effect, said bimetallic strip being constructed so as to retract from the path of gas passing through said burner body when said bimetallic strip is heated to reduce the obstruction to the flow of gas there- 5 in and thereby permit the induction of a greater quantity of primary air into said burner.

2. A gas furnace comprising a heat exchanger and a burner body disposed in said heat exchanger, said heat exchanger being initially subject to the existence of a resonance effect upon ignition of said burner, said burner body comprising an elongated, hollow, sheet metal memher having an open end for receiving gas and primary air, and a burner port for discharging a mixture of gas and primary air from the interior of said burner body into an atmosphere of secondary air in said heat exchanger for burning of said gas; a gas supply manifold having a gas orifice therein disposed to project a stream of gas into said open end of said burner body, said burner body being arranged so that passage of gas from said gas orifice through said burner body induces primary air into said burner body for mixture therein and passage of said mixture through said burner port, temperature actuated means disposed Within said burner body, said temperature actuated means having a temperature sensitive element disposed in the stream of mixed fuel and primary air in said burner body, said temperature actuated means being arranged to restrict the free flow of gas through the interior of said burner body when the sensed temperature is relatively low to thereby limit the quantity of primary air induced into said burner body to an amont which does not give rise to a resonance effect, said temperature actuated means automatically reducing the restriction to the flow of gas through the interior of said burner body when the sensed temperature is relatively higher to thereby induce a greater quantity of primary air into said burner body.

References Cited by the Examiner UNITED STATES PATENTS 2,362,259 11/44 Findley l581l8 X 2,364,299 12/44 Kester 158-118 2,652,108 9/53 Jenkins 15S-118 JAMES W. WESTHAVER, Primary Examiner.

MEYER PERLIN, Examiner. 

1. A BURNER ASSEMBLY FOR BURNING A COMBUSTIBLE GASEOUS FUEL MIXED WITH AIR WHICH COMPRISES: AN ELONGATED HOLLOW SHEET METAL BURNER BODY ADAPTED TO BE OPERATIVELY POSITIONED IN A COMBUSTION CHAMBER SUBJECT TO A REASONANCE CONDITION WHEN SAID BURNER IS IGNITED, SAID BURNER BODY HAVING AN OPEN END FOR RECEIVING A STREAM OF GAS TO BE BURNED AND FOR RECEIVING A QUANTITY OF PRIMARY AIR INDUCED INTO SAID BURNER BODY HAVING A BURNER OF SAID STREAM OF GAS, SAID BURNER BODY HAVING A BURNER PORT FOR DISCHARGING A MIXTURE OF GAS AND PRIMARY AIR FROM SAID BURNER BOIDY INTO AN ATMOSPHERE OF SECONDARY AIR IN SAID COMBUSTION CHAMBER FOR BURNING OF SAID GAS, A BIMETALLIC STRIP ATTACHED TO SAID BURNER BODY AND PROJECTING INTO THE HOLLOW INTERIOR THEREOF IN CONTACT WITH THE STREAM OF MIXED FUEL AND PRIMARY AIR THEREIN, SAID BIMETALLIC STRIP BEING ARRANGED TO OBSTRUCT FLOW OF GAS THROUGH SAID BURNER BODY WHEN SAID BIMETALLIC STRIP IS IN A RELATIVELY COLD CONDITION SO AS TO LIMIT THE QUANTITY OF PRIMARY AIR INDUCED INTO SAID BURNER BODY BY SAID GAS STREAM TO AN AMOUNT WHICH DOES NOT GIVE RISE TO SAID RESONANCE EFFECT, SAID BIMETALLIC STRIP BEING CONSTRUCTED SO AS TO RETRACT FROM THE PATH OF GAS PASSING THROUGH SAID BURNER BODY WHEN SAID BIMETALLIC STRIP IS HEATED TO REDUCE THE OBSTRUCTION TO THE FLOW OF GAS THEREIN AND THEREBY PREMIT THE INDUCTION OF A GREATER QUANTITY OF PRIMARY AIR INTO SAID BURNER. 